% Acknowledgments

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%As so many PhD students before me have stated in this very spot, this thesis and the research describe herein could not have been realized without the support of many others. Although I doubt I can do proper justice to everyone's contributions in just two pages of text, I will give it my best shot. And if I have managed to overlook someone accidentally, please know that I am as grateful to you as I am to everyone who supported me in the past years.

First and foremost I would like to thank my supervisor and promotor Antal van den Bosch, who guided me in my first steps as a researcher, both for my Master's thesis and my Ph.D.\ research. Antal always gave me free reign in investigating many different research problems, while at the same time managing to steer me in the right direction when the time called for it. Antal was always able to make time for me or any of the other Ph.D.\ students, and read and comment on paper or presentation drafts.

In addition to turning me into a better researcher, Antal was also instrumental in improving my Guitar Hero skills. Our thesis meetings during your sabbatical doubled as a kind of Rock 'n Roll Fantasy Camp, where we could both unwind from discussing yet another batch of experiments I had run or was planning to run. Rock on! Antal also shares my passion for ice hockey. This resulted in us attending Tilburg Trappers games in Stappegoor as well as our regular discussions of the latest hockey news. Thanks for inviting me to come see the NHL All Star games in Breda. Hopefully we will meet again in spirit come May 2010 when the Canucks beat the Penguins in the Stanley Cup finals! %And Antal, I regret that I could not leave in any references to pirates, ninjas or aliens as I am prone to do in abstract drafts, but rest assured that you have not seen the last of them!

The research presented in this thesis was performed in the context of the \`{A} Propos project. I would like to acknowledge SenterNovem and the Dutch Ministry of Economic Affairs for funding this project as part of the IOP-MMI program. The \`{A} Propos project was started by Lou Boves, Antal, and Frank Hofstede. I would like to thank Lou and Frank in particular. Frank was always able to look at my research problems from a different and more practical angle, and as a result our discussions were always very stimulating. I would also like to Mari Carmen Puerta-Melguizo, Anita Deshpande, and Els den Os, as well as the other members and attendees of the project meetings for the pleasant cooperation and helpful comments and suggestions.

I wish to thank the members of my committee for taking time out of their busy schedules to read my dissertation and attending my defense: Jaap van den Herik, Maarten de Rijke, Lou Boves, Birger Larsen, and Hans Paijmans. Special thanks go to Jaap for his willingness to go through my thesis with a fine-grained comb. The readability of the final text has benefited greatly from his meticulous attention to detail and quality. Any errors remaining in the thesis are my own. I would also like to thank Birger for his comments, which helped to dot the i's and cross the t's of the final product. Finally, I would like to thank Hans Paijmans, who contributed considerably to my knowledge of IR.

My Ph.D.\ years would not have been as enjoyable and successful without my colleagues at Tilburg University, especially those at the ILK group. It is not everywhere that the bond between colleagues is as strong as it was in ILK and I will not soon forget the coffee breaks with the Sulawesi Boys, the BBQs and Guitar Hero parties, lunch runs, after-work drinks, and the friendly and supportive atmosphere on the 3rd floor of Dante. I do not have enough room to thank everyone personally here, you know who you are. In your own way, you all contributed to this thesis. %And although inanimate, I would also like to recognize our trusted servers IO, Erebus, Phoenix, Chronos, Sphinx, and Aether for contributing as much to this thesis as I did myself.

Over the course of my Ph.D.\ I have spent many Fridays at the Science Park in Amsterdam, working with members of the ILPS group headed by Maarten de Rijke. I would like to thank Erik Tjong Kim Sang for setting this up and Maarten for allowing me to become a guest researcher at his group. Much of what I know about doing IR research, I learned from these visits. From small things like visualizing research results and LaTeX layout to IR research methodology and a focus on empirical, task-driven research. I hope that some of what I have learned shows in the thesis. I would like to thank all of the ILPS members, but especially Krisztian, Katja, and Maarten for collaborating with me on expert search, which has proven to be a very fruitful collaboration so far.

I have also had the pleasure of working at the Royal School of Library and Information Science in Copenhagen. I am most grateful to Birger Larsen and Peter Ingwersen, for helping to arrange my visit and guiding me around. Thanks are also due to Mette, Haakon, Charles, Jette, and the other members of the IIIA group for welcoming me and making me feel at home. Jeg gl\ae der mig til at arbejde sammen med jer snart.

Thanks are due to Sunil Patel for designing part of the stylesheet of this thesis and to Jonathan Feinberg of \url{http://www.wordle.net/} for the word cloud on the front of this thesis. I owe Maarten Clements a debt of gratitude for helping me to more efficiently implement his random walk algorithm. And of course thanks to \bib, \cul, and \del\ for making the research described in this thesis possible.

Finally, I would like to thank the three most important groups of people in my life. My friends, for always supporting me and taking my mind off my work. Thanks for all the dinners, late-night movies, pool games, talks, vacations and trips we have had so far! Thanks to my parents for always supporting me and believing in me; without you I would not have been where I am today. Kirstine, thanks for putting up with me while I was distracted by my work, and thanks for patiently reading and commenting on my Ph.D.\ thesis. Og tusind tak fordi du bringer s\aa\ meget gl\ae de, latter og k\ae rlighed ind i mit liv. Det her er til Timmy og Oinky!

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